Rated power of stepper motor?

[schnell]

Do you know what is the rated power of this stepper motor?

It is the 6V, 18.5 Ohms per winding (UBB1/5) type…….

http://www.auf-vertrieb.business.t-online.de/pdf/UBB.pdf

-the stepper has two windings.

Am I right in assuming that this stepper motor’s rated power is 2 * V^2/R = 3.89W ?


If the rated power is indeed this figure of 3.89W, is it ever permissible/adviseable to drive this stepper motor with a power higher than this rated value?

-If so , then for how long may I drive the stepper motor at a power level which is higher than the motors rated power level?

 

[cswilson]

The V^2/R term you suggest is a power dissipation term (without movement), not at all relevant to the rated power of a motor.

The rated power of a motor involves the power that can be delivered to the mechanical system -- torque times speed. Really, this is not a single number, but a curve. The curves of power vs speed are shown in the thick dashed lines in the plots of the link you provide. These peak at less than 1W for your motor.

Curt Wilson
Delta Tau Data Systems

 

[schnell]

thankyou for that.

Our stepper motors drive valves in water pipes and much of the time, the stepper motor is stationary, holding the water flow at a certain level.

-so in other words, the speed is zero.
-I hope you will forgive me for wondering what is the maximum power when stationary for this stepper motor, since Torque*Speed will then be zero?

 

[cswilson]

When stationary, the power transferred to the mechanical system is zero, because the speed is zero.

The power consumed from the electrical system by the motor will be the V^2/R that you originally suggested (although probably for only one phase.

Curt Wilson
Delta Tau Data Systems